100 Francs CFA Rhodium

The Republic of the Congo has issued a series of fractional gold pieces marketed around rare and exotic elements, of which rhodium — the world's most expensive naturally occurring metal by weight — makes for an ironic pairing with a coin whose gold content is a half-gram. Rhodium's price has swung from roughly $640 per troy ounce in 2016 to over $29,000 in early 2021 before collapsing again, a volatility that makes it a peculiar subject for a coin meant to convey permanence and value.